Toward white lasers: organic widely real-time tunable emitters

Abstract

Tunability is an important aspect of lasers. Nowadays there are many possible ways to achieve this advantageous property; however, dynamic tuning is limited. Red to InfraRed emissive dyes allow a direct visualization of molecular interactions, through deep tissue penetration, along with minimal tissue damage. In our studies we use simple systems based on a single dye-doped polymeric thin films for distributed feedback (DFB) and random lasing (RL) investigations. As active compounds we have applyed novel push-pull luminescent diphenylaminofluorene and tiophene derivatives, with different acceptor groups. Integration of such luminescent dyes with transparent polymeric medium allows fabricating real-time lasing tunability in the visible region and first biological window (650-950 nm). The observed spectral tuning of 150 nm is a groundbreaking value obtained in a single-dye system. Also Excited-State Intramolecular Proton Transfer (ESIPT) compounds, have attracted our considerable attention, due to their unique optical properties. In this contribution we show a novel bis-trimethylsilyl substituted 2-(2’hydroxyphenyl)benzothiazole (HBT) derivatives functionalized with a trifluoromethyl - a strong electron-withdrawing group. Such structure enabled real-time red-green-blue (RGB) switching of emission, both in solution and solid-state, providing white laser light emission. We show strong dependence on environment polarity, as well as Aggregation-Induced Emission Enhancement (AIEE) properties, and successful implementation of ESIPT molecules in DFB lasing, both in solution and solid-state.